Field of the Invention
The invention relates, in general, to firearms and in particular to a new and useful insert gun barrel with adjusting device of the front insert barrel bearing.
To train the gunner and the commander of combat tanks for sighting under combat conditions, shooting from the gun on exercise grounds is an indispensible requirement. To lower the costs for diversified sighting training, there is used a socalled training equipment of a caliber which is smaller than the caliber of the barrel of the tank gun. It is crucial for the development of such an insert barrel as training equipment to obtain valid information about the accuracy of fire. For it would be psychologically wrong to train the soldier with an equipment of an accuracy of fire substantially inferior to what is possible with the original weapon. Therefore, the insert barrel must provide the possibility of equalizing the accuracy of fire for different types of ammunition, such as tank ammunition and subcaliber ammunition. If no precautions were provided for adjusting the insert barrel to a combat tank gun, a different mean point of impact would be obtained than is obtained with the normal combat tank ammunition from the combat tank barrel. The causes of this are deviations in the type of ammunition, sag or curvature of the barrels, manufacturing tolerances, and different lengths of the two barrels.
To bring the different off positions to a common mean point of impact, the insert barrel system must be trial-fired with the respective ammunition and the gun system must be given a basic setting. These operations are relatively time-consuming, and due to the repeated trial firing they result in high ammunition costs and heavy wear on the insert barrel system.
From German publication No. 12 05 759 a trial firing device for practice weapons has become known where by means of an adjusting device the front end of the insert barrel is adjustable diametrically in a straight line. The front part of the insert barrel is present between two eccentrics, which in turn are supported in openings of rotatable disks. To achieve adjustment of the insert barrel, it is necessary, after unscrewing screws, to rotate the disks, which causes them to take the eccentrics along. This rotation takes place up to a mark on a scale. By the rotation of the disks with the diametrical clamping device, the adjustability is brought into the radius of the established firing deviation of the axis of the bore of the insert barrel. With the aid of the two eccentrics the front end of the insert barrel is then displaced diametrically in a straight line, this being possible by a serration on the eccentrics. Lastly, both eccentrics are brought to abut against the barrel and the occupied position is secured by tightening screws.
Due to the many structural parts, such a device for adjustment of the insert barrel is relatively costly and complicated to adjust. Several successive operations are always necessary to obtain the desired position of the front end of the insert barrel.